This retarded thinking of mine (I really wonder what kind of retardation I have, because I'm pretty sure there's something unusual, at least) - resulted in an idea, though. Maybe this already is some existing effect - if so, anyone know the definition?
So, again, you take two signals, create a sum, and difference out of them; and then you simply modulate between hearing one or the other (sort of crossfading - if you use a square modulator then you rapidly switch between hearing sum, then difference).
Don't expect drastic changes with very different sound sources ~ but it rather gets interesting, if you take 1 sound, make a duplicate, where you change - say, its pitch, and then take the two and start the above experiment.
Is this crazy, or stupid?
Fitting silliness:
(Sticks is crazy, Knuckles [red guy] is stupid.)
[Everyone should watch Sonic Boom!]